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Title: ULTRAVIOLET PROPERTIES OF GALACTIC GLOBULAR CLUSTERS WITH GALEX. II. INTEGRATED COLORS

Abstract

We present ultraviolet (UV) integrated colors of 44 Galactic globular clusters (GGCs) observed with the Galaxy Evolution Explorer (GALEX) in both FUV and NUV bands. This database is the largest homogeneous catalog of UV colors ever published for stellar systems in our Galaxy. The proximity of GGCs makes it possible to resolve many individual stars even with the somewhat low spatial resolution of GALEX. This allows us to determine how the integrated UV colors are driven by hot stellar populations, primarily horizontal branch stars and their progeny. The UV colors are found to be correlated with various parameters commonly used to define the horizontal branch morphology. We also investigate how the UV colors vary with parameters like metallicity, age, helium abundance, and concentration. We find for the first time that GCs associated with the Sagittarius dwarf galaxy have (FUV - V) colors systematically redder than GGCs with the same metallicity. Finally, we speculate about the presence of an interesting trend, suggesting that the UV color of GCs may be correlated with the mass of the host galaxy, in the sense that more massive galaxies possess bluer clusters.

Authors:
; ;  [1];  [2]; ;  [3];  [4]
  1. Dipartimento di Astronomia, Universita degli Studi di Bologna, via Ranzani 1, I-40127, Bologna (Italy)
  2. Gemini Observatory, 670 N. A'Ohoku Place, Hilo, HI 96720 (United States)
  3. Astronomy Department, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States)
  4. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
Publication Date:
OSTI Identifier:
22089835
Resource Type:
Journal Article
Journal Name:
Astronomical Journal (New York, N.Y. Online)
Additional Journal Information:
Journal Volume: 144; Journal Issue: 5; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1538-3881
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; ASTROPHYSICS; CATALOGS; COLOR; ELEMENT ABUNDANCE; GALAXIES; HELIUM; MASS; MORPHOLOGY; SPATIAL RESOLUTION; STAR CLUSTERS; STARS; ULTRAVIOLET RADIATION

Citation Formats

Dalessandro, Emanuele, Ferraro, Francesco R., Lanzoni, Barbara, Schiavon, Ricardo P., Rood, Robert T., O'Connell, Robert W., and Sohn, Sangmo T. ULTRAVIOLET PROPERTIES OF GALACTIC GLOBULAR CLUSTERS WITH GALEX. II. INTEGRATED COLORS. United States: N. p., 2012. Web. doi:10.1088/0004-6256/144/5/126.
Dalessandro, Emanuele, Ferraro, Francesco R., Lanzoni, Barbara, Schiavon, Ricardo P., Rood, Robert T., O'Connell, Robert W., & Sohn, Sangmo T. ULTRAVIOLET PROPERTIES OF GALACTIC GLOBULAR CLUSTERS WITH GALEX. II. INTEGRATED COLORS. United States. doi:10.1088/0004-6256/144/5/126.
Dalessandro, Emanuele, Ferraro, Francesco R., Lanzoni, Barbara, Schiavon, Ricardo P., Rood, Robert T., O'Connell, Robert W., and Sohn, Sangmo T. Thu . "ULTRAVIOLET PROPERTIES OF GALACTIC GLOBULAR CLUSTERS WITH GALEX. II. INTEGRATED COLORS". United States. doi:10.1088/0004-6256/144/5/126.
@article{osti_22089835,
title = {ULTRAVIOLET PROPERTIES OF GALACTIC GLOBULAR CLUSTERS WITH GALEX. II. INTEGRATED COLORS},
author = {Dalessandro, Emanuele and Ferraro, Francesco R. and Lanzoni, Barbara and Schiavon, Ricardo P. and Rood, Robert T. and O'Connell, Robert W. and Sohn, Sangmo T.},
abstractNote = {We present ultraviolet (UV) integrated colors of 44 Galactic globular clusters (GGCs) observed with the Galaxy Evolution Explorer (GALEX) in both FUV and NUV bands. This database is the largest homogeneous catalog of UV colors ever published for stellar systems in our Galaxy. The proximity of GGCs makes it possible to resolve many individual stars even with the somewhat low spatial resolution of GALEX. This allows us to determine how the integrated UV colors are driven by hot stellar populations, primarily horizontal branch stars and their progeny. The UV colors are found to be correlated with various parameters commonly used to define the horizontal branch morphology. We also investigate how the UV colors vary with parameters like metallicity, age, helium abundance, and concentration. We find for the first time that GCs associated with the Sagittarius dwarf galaxy have (FUV - V) colors systematically redder than GGCs with the same metallicity. Finally, we speculate about the presence of an interesting trend, suggesting that the UV color of GCs may be correlated with the mass of the host galaxy, in the sense that more massive galaxies possess bluer clusters.},
doi = {10.1088/0004-6256/144/5/126},
journal = {Astronomical Journal (New York, N.Y. Online)},
issn = {1538-3881},
number = 5,
volume = 144,
place = {United States},
year = {2012},
month = {11}
}